From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: RAID1, hot-swap and boot integrity Date: Tue, 06 Mar 2007 18:17:04 -0500 Message-ID: <45EDF670.9010806@tmr.com> References: <45E82EF8.9000106@laurelnetworks.com> <12470.45E88FAA.5020106@tmr.com> <45ECA9E9.3090507@laurelnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <45ECA9E9.3090507@laurelnetworks.com> Sender: linux-raid-owner@vger.kernel.org To: Mike Accetta Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Mike Accetta wrote: > Bill Davidsen wrote: >> Gabor Gombas wrote: >>> On Fri, Mar 02, 2007 at 09:04:40AM -0500, Mike Accetta wrote: >>> >>> >>>> Thoughts or other suggestions anyone? >>>> >>> >>> This is a case where a very small /boot partition is still a very good >>> idea... 50-100MB is a good choice (some initramfs generators require >>> quite a bit of space under /boot while generating the initramfs image >>> esp. if you use distro-provided >>> "contains-everything-and-the-kitchen-sink" >>> kernels, so it is not wise to make /boot _too_ small). >>> >> You are exactly right on that! Some (many) BIOS implementations will >> read the boot sector off the drive, and if there is no error will run >> the boot sector. >>> But if you do not want /boot to be separate a moderately sized root >>> partition is equally good. What you want to avoid is the "whole disk is >>> a single partition/file system" kind of setup. >>> >>> >> Actually, the solution is moderately simple, install the replacement >> drive, create the partitions, and **don't mark the boot partition >> active** until the copy is complete. The BIOS will boot from the 1st >> active partition it finds (again, in sane cases). >> >> I never have anything changing in /boot in normal operation, so I >> admit to using dd to do a copy with the array stopped. No particular >> reason to think it works better than just a rebuild. After the >> partition is valid I set the active flag in the partition. >> > > I gathered the impression somewhere, perhaps incorrectly, that the active > flag was a function of the boot block, not the BIOS. We use Grub in > the MBR > and don't even have an active flag set in the partition table. The > system > still boots. Now that you mention that, I have been doing the active bit thing since pre-grub (possibly pre-lilo) days, so it may not be effective with grub in the MBR. Something to add to my list of "when I'm bored and want to try something" list. Thanks for making the point. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979